1. Field of the Invention
The invention relates to an automatic roll-up device for a safety belt with a mechanism for blocking the belt roller in case of danger, which can be automatically activated by a control element when a predetermined acceleration or deceleration of the vehicle is exceeded.
2. Description of the Prior Art
In the known automatic roll-up devices for safety belts (U.S. Pat. No. 3,901,459) a wind-up spring is arranged at one side of the belt roller which is fastened in a stable housing, while the opposite shaft end is in connection with a locking pawl mechanism and a release mechanism, whereby in the case of danger, i.e. in the case of an accident, the release mechanism, for example of the inertial mass type, acts on a control disc and said control disc effects through the locking pawl mechanism the blocking of the belt band. In this system, the total pulling force acts on the locking pawl mechanism and on the belt shaft so that these parts must be very strong and massive to withstand the extremely high pull-forces in case of danger.
On the other hand, braking- or clamping devices for belt bands have been described (Great Britain-Patent Specification No. 1,416,517, German Pulbished Non-Prosecuted Application No. 19 49 061), wherein the belt is deflected over several brake rollers, so that at the occurrence of a pulling force, the belt is braked by the thereby created friction forces, or wherein the belt is mechanically fixed by pressure between clamping jaws or clamping rollers, and is prevented from being pulled out any further.